THE vaccine developed by Bejing-based Sinovac Biotech Ltd. was effective in controlling COVID-19 in a mass inoculation study in a small Brazilian town after 75 percent of adults were covered with a second shot, preliminary numbers show.

The study carried out by the Sao Paulo state government in the small town of Serrana, with a population of 45,000, may offer clues for other developing nations on how much of the public needs to be vaccinated in order to begin moving past the pandemic that continues to wreak havoc in Latin America and beyond.

While infection rates improved after first doses were administered, COVID-19 wasn’t properly controlled in the town until after a second shot was given. A complete study will be published soon.

The study was led by the Butantan Institute, which produces Sinovac’s CoronaVac in Brazil. Almost two-thirds of Serrana’s inhabitants got the vaccine between February and April with another third ineligible to receive the shot if they were under 18 years old or pregnant. About 95 percent of the targeted adult population received the required two doses in the study.

“This is the first study of its kind in the world,” Dimas Covas, Butantan’s director, said at a press conference Monday. “This is primary data on the effects of vaccination in a population that will help authorities develop public policies.”

While neighboring cities were being hit hard by the pandemic, Serrana saw deaths fall by 95 percent in the five weeks right after the mass vaccination was completed. Symptomatic cases dropped by 80 percent and hospitalizations decreased by 86 percent.

“Now we can say that it’s possible to control the pandemic with vaccines,” said Ricardo Palacios, research director at Butantan, adding that COVID-19 numbers also fell for children. “This shows that it isn’t necessary to vaccinate children to open schools,” Palacios said.

No severe side effects from the vaccine were reported and there were no COVID-related deaths among participants 14 days after the second dose was applied. The area around Serrana, some 315 kilometers (195 miles) from Sao Paulo, was overrun by the P1 variant during the study, reaffirming the jab’s effectiveness against the strain first found in Brazil, Palacios said.

The results in Serrana offer hope to hundreds of millions of people, especially in developing nations. Egypt, Pakistan, Indonesia, Zimbabwe and others are likewise reliant on the Chinese shot, which is cheaper than vaccines from Pfizer and Moderna.

The findings also underline the importance of people returning for a second shot. In Brazil, some 66 million vaccines have been administered, covering 21.4 percent of the population with a single dose. About 10.5 percent of the country is now considered to be fully inoculated. (SD-Agencies)